Resistance element for resistance thermometer and process for its manufacturing

Abstract

There is provided a means for measuring resistance for a resistance thermometer consisting of an insulating former as a carrier and a thin platinum layer as resistance material, the carrier for the platinum layer being made of a material having a greater thermal coefficient of expansion than platinum over the range between 0° and 1000° C.

What is claimed is: 
     
       1. A resistance element for a resistance thermometer consisting essentially of an insulating body as a support and a thin platinum layer thereon as the resistance material, said support being made of a material having a greater thermal coefficient of expansion greater than platinum between the range of 0° to 1000° C. 
     
     
       2. A resistance element according to claim 1 wherein the support comprises magnesium oxide. 
     
     
       3. A resistance element according to claim 1 wherein the platinum layer has a thickness of 1 to 10 microns. 
     
     
       4. A resistance thermometer including the resistance element of claim 1. 
     
     
       5. A resistance thermometer according to claim 4 wherein the support consists essentially of magnesium oxide. 
     
     
       6. A resistance thermometer according to claim 4 comprising the resistance element in a protective tube. 
     
     
       7. A resistance element according to claim 1 having a TCR of 3.85 × 10 -3 . 
     
     
       8. A resistance thermometer including the resistance element of claim 7. 
     
     
       9. A resistance element according to claim 7 wherein the support is made of a nickel alloy with an insulating coating. 
     
     
       10. A resistance element according to claim 1 wherein the support is made of a nickel alloy, with an insulating coating. 
     
     
       11. A resistance element according to claim 10 wherein the insulating coating consists of magnesium oxide, aluminum oxide or a silicate glass. 
     
     
       12. A resistance element according to claim 10 wherein the insulating coating consists of magnesium oxide or aluminum oxide. 
     
     
       13. A resistance element according to claim 12 wherein the insulating coating consists of magnesium oxide. 
     
     
       14. A resistance element according to claim 10 wherein the nickel alloy is a nickel, chromium, iron alloy. 
     
     
       15. A resistance element according to claim 14 wherein the alloy is 80 Ni, 14 Cr, 6 Fe. 
     
     
       16. A resistance element according to claim 15 wherein the insulating coating consists of magnesium oxide, aluminum oxide or a silicate glass. 
     
     
       17. A resistance element according to claim 16 wherein the insulating coating consists of magnesium oxide or aluminum oxide. 
     
     
       18. A resistance element according to claim 17 wherein the insulating coating consists of magnesium oxide. 
     
     
       19. A resistance element according to claim 15 having a TCR of 3.85 × 10 -3 . 
     
     
       20. A process of producing the resistance element of claim 19 comprising applying the thin platinum layer to the support by cathode sputtering in an oxygen containing atmosphere and thereafter tempering at a temperature above 800° C. 
     
     
       21. The process of claim 20 wherein the oxygen containing atmosphere consists essentially of oxygen and an inert gas. 
     
     
       22. The process of claim 21 wherein the atmosphere consists of an argon-oxygen mixture. 
     
     
       23. The process of claim 21 wherein the tempering is at a temperature up to 1200° C. 
     
     
       24. The process of claim 21 wherein the oxygen content of the atmosphere is 5 to 60 volume %, the balance being inert gas. 
     
     
       25. The process of claim 24 wherein the inert gas is argon. 
     
     
       26. The process of claim 25 wherein the tempering is at 1000° to 1200° C. 
     
     
       27. The process of claim 26 wherein the insulating coating comprises magnesium oxide. 
     
     
       28. A process according to claim 20 wherein the support is made of a nickel alloy having an insulating coating comprising magnesium oxide, aluminum oxide or a silicate glass. 
     
     
       29. A process according to claim 28 wherein the nickel alloy is a nickel, chromium, iron alloy. 
     
     
       30. A process according to claim 28 wherein the insulating coating comprises magnesium oxide. 
     
     
       31. A resistance element according to claim 29 wherein the insulating coating comprises magnesium oxide or aluminum oxide. 
     
     
       32. A resistance element according to claim 31 wherein the insulating coating comprises magnesium oxide.